| tridinski |
15.04.2025 13:21 |
Zitat:
Zitat von sabine-g
(Beitrag 1779640)
Ich bin Reifen (23er ) mit 5-6 Bar und mit 8Bar gefahren.
Mit 8Bar war ich schneller bei gleicher Leistung.
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Das ist sehr gut möglich. Auf einer anderen, raueren Strasse, wäre das Ergebnis ggf. anders gewesen. Dazu folgender Text:
Zitat:
Suspension drag is the loss of speed, or efficiency to be precise, of an object in forward motion due to vibrations, bumps or other vertical movement. Or, to put it differently, any vertical movement will cause the object to have less energy propelling it forward. In cycling, the greatest cause for that vertical movement is the road surface.
These suspension losses, as they are most frequently called, factor into a bike tyre's overall rolling resistance. Thus, rolling resistance in a lab test is very different from rolling resistance on the actual road. Regardless of what the lab test says is most efficient, that test is only accounting for the hysteretic losses of a tyre – the energy lost as heat due to the continuous deformation and flexing of the tyre as it makes contact with the road while rolling. Accurately assessing the suspension losses, which are the counterparts to hysteretic losses, is virtually impossible on a drum because road surfaces are inconsistent.
“If you test tyres in the lab, you're only measuring the hysteretic losses in the tyre casing, and so generally the harder you pump up the tyre, the less losses you have,” Jan Heine told Cycling Weekly. Heine is the CEO of the tyre company Rene Herse and is an expert on the matter.
“But when we started testing on real roads, we found that that's not true at all. Lower pressures roll just as fast. From that point, we realised we don't need narrow tyres, because at lower pressures, we can make wider tyres with supple casings. But the big question we still had was, why do we see such different behavior on the road compared to in the lab?”
Heine credits Jim Papadopoulos, a former tech expert, for uncovering a key insight to this question in his book Cycling Science. Papadopoulos referenced a United States Army study on tank vibrations, where the drivers absorbed 2000 watts from vibrations. This led to the realisation that energy loss from vibrations was slowing down the vehicle. Heine notes that lab tests, which didn’t account for the rider or uneven surfaces, missed this important factor in measuring energy loss on bikes.
In cycling, we’re dealing with much smaller forces and, at least on tarmac, fewer vibrations, yet the physics are the same – vibration is an enemy of forward movement and one that’s undervalued in cycling at large.
“[Tyre size] almost doesn't matter, because the suspension losses and the hysteretic losses balance each other out,” Heine said about what he finds to be the right width on smooth tarmac.
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Yet, whenever the road has any kind of imperfections, the width must go up to balance the equation.
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Quelle: https://www.cyclingweekly.com/review...-pay-attention |
